PCI: Look for unassigned resources on per-bus basis

When CONFIG_PCI_REALLOC_ENABLE_AUTO=y, pci_realloc_detect() looks at PCI
devices to see if any have SR-IOV resources that need to be assigned.  If
it finds any, it turns on automatic resource reallocation.

This patch changes pci_realloc_detect() so it uses pci_walk_bus() on
each root bus instead of using for_each_pci_dev().  This is a step
toward doing reallocation on a per-bus basis, so we can do it for
a hot-added host bridge.

[bhelgaas: changelog, rename callback to iov_resources_unassigned(), use
boolean for "unassigned"]
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

1 files changed, 29 insertions, 15 deletions

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index cb6bcbb26226..20c09bd652db 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -1359,30 +1359,44 @@ static bool __init pci_realloc_enabled(void)
         return pci_realloc_enable >= user_enabled;
 }
 
-static void __init pci_realloc_detect(void)
-{
 #if defined(CONFIG_PCI_IOV) && defined(CONFIG_PCI_REALLOC_ENABLE_AUTO)
-        struct pci_dev *dev = NULL;
+static int __init iov_resources_unassigned(struct pci_dev *dev, void *data)
+{
+        int i;
+        bool *unassigned = data;
 
-        if (pci_realloc_enable != undefined)
-                return;
+        for (i = PCI_IOV_RESOURCES; i <= PCI_IOV_RESOURCE_END; i++) {
+                struct resource *r = &dev->resource[i];
 
-        for_each_pci_dev(dev) {
-                int i;
+                /* Not assigned or rejected by kernel? */
+                if (r->flags && !r->start) {
+                        *unassigned = true;
+                        return 1; /* return early from pci_walk_bus() */
+                }
+        }
 
-                for (i = PCI_IOV_RESOURCES; i <= PCI_IOV_RESOURCE_END; i++) {
-                        struct resource *r = &dev->resource[i];
+        return 0;
+}
 
-                        /* Not assigned, or rejected by kernel ? */
-                        if (r->flags && !r->start) {
-                                pci_realloc_enable = auto_enabled;
+static void  __init pci_realloc_detect(void)
+{
+        bool unassigned = false;
+        struct pci_bus *bus;
 
-                                return;
-                        }
+        if (pci_realloc_enable != undefined)
+                return;
+
+        list_for_each_entry(bus, &pci_root_buses, node) {
+                pci_walk_bus(bus, iov_resources_unassigned, &unassigned);
+                if (unassigned) {
+                        pci_realloc_enable = auto_enabled;
+                        return;
                 }
         }
-#endif
 }
+#else
+static void __init pci_realloc_detect(void) { }
+#endif
 
 /*
  * first try will not touch pci bridge res